1PCP-IOSTAT(1) General Commands Manual PCP-IOSTAT(1)
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6 pmiostat, pcp-iostat - report block I/O statistics
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9 pcp [pcp options] iostat [-u] [-G method] [-P precision] [-R pattern]
10 [-x [dm][,t][,h][,noidle]]
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13 pcp-iostat reports I/O statistics for SCSI (by default) or other
14 devices (if the -x option is specified).
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17 When invoked via the pcp(1) command, the -a/--archive, -h/--host,
18 -O/--origin, -s/--samples, -t/--interval, -Z/--timezone and several
19 other pcp options become indirectly available; refer to PCPIntro(1) for
20 a complete description of these options.
21 The additional command line options available for pcp-iostat are:
23 -G method, --aggregate=method
25 Specifies that statistics for device names matching the regular
26 expression specified with the -R regex option should be aggregated
27 according to method. Note this is aggregation based on matching
28 device names (not temporal aggregation). When -G is used, the
29 device name column is reported as method(regex), e.g. if -G sum
30 -R 'sd(a|b)$' is specified, the device column will be
31 sum(sd(a|b)$) and summed statistics for sda and sdb will be
32 reported in the remaining columns. If -G is specified but -R is
33 not specified, then the default regex is .*, i.e. matching all
34 device names. If method is sum then the statistics are summed.
35 This includes the %util column, which may therefore exceed 100% if
36 more than one device name matches. If method is avg then the sta‐
37 tistics are summed and then averaged by dividing by the number of
38 matching device names. If method is min or max, the minimum or
39 maximum statistics for matching devices are reported, respec‐
40 tively.
41 -P N, --precision=N
43 This indicates the precision (number of decimal places) to report.
44 The default precision N may be set to something other than the
45 default (2). Note that the avgrq-sz and avgqu-sz fields are
46 always reported with N+1 decimals of precision. These fields typ‐
47 ically have values less than 1.
48 -R pattern, --regex=pattern
50 This restricts the report to device names matching a regular
51 expression pattern. The given pattern is searched as a perl style
52 regular expression, and will match any portion of a device name.
53 e.g. '^sd[a-zA-Z]+' will match all device names starting with 'sd'
54 followed by one or more alphabetic characters. e.g. '^sd(a|b)$'
55 will only match 'sda' and 'sdb'. e.g. 'sda$' will match 'sda' but
56 not 'sdab'. See also the -G option for aggregation options.
57 -u, --no-interpolation
59 When replaying a set of archives, by default values are reported
60 according to the requested sample interval (-t option), not
61 according to the actual interval recorded in the archive(s).
62 Without this option PCP interpolates the values to be reported
63 based on the records in the set of archives, which is particularly
64 useful when the -t option is used to replay a set of archives with
65 a longer sampling interval than that with which the archive(s) was
66 originally recorded with. With the -u option, uninterpolated
67 reporting is enabled - every value is reported according to the
68 native recording interval in the set of archives. When the -u
69 option is specified, the -t option makes no sense and is incompat‐
70 ible because the replay interval is always the same as the record‐
71 ing interval in the set of archive. In addition, -u only makes
72 sense when replaying archives, see the -a option on PCPIntro(1),
73 and so if -u is specified then -a must also be specified.
74 -x comma-separated-options
76 Specifies a comma-separated list of one or more extended reporting
77 options as follows:
78 dm - report statistics for device-mapper logical devices instead
79 of SCSI devices,
80 t - prefix every line in the report with a timestamp in ctime(3)
81 format,
82 h - omit the heading, which is otherwise reported every 24 sam‐
83 ples,
84 noidle - Do not display statistics for idle devices.
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87 The columns in the pcp-iostat report have the following interpretation:
88 Timestamp
90 When the -x t option is specified, this column is the timestamp
91 in ctime(3) format.
92 Device Specifies the scsi device name, or if -x dm is specified, the
94 device-mapper logical device name. When -G is specified, this
95 is replaced by the aggregation method and regular expression -
96 see the -G and -R options above.
97 rrqm/s The number of read requests expressed as a rate per-second that
99 were merged during the reporting interval by the I/O scheduler.
100 wrqm/s The number of write requests expressed as a rate per-second that
102 were merged during the reporting interval by the I/O scheduler.
103 r/s The number of read requests completed by the device (after
105 merges), expressed as a rate per second during the reporting
106 interval.
107 w/s The number of write requests completed by the device (after
109 merges), expressed as a rate per second during the reporting
110 interval.
111 rkB/s The average volume of data read from the device expressed as
113 KBytes/second during the reporting interval.
114 wkB/s The average volume of data written to the device expressed as
116 KBytes/second during the reporting interval.
117 avgrq-sz
119 The average I/O request size for both reads and writes to the
120 device expressed as Kbytes during the reporting interval.
121 avgqu-sz
123 The average queue length of read and write requests to the
124 device during the reporting interval.
125 await The average time in milliseconds that read and write requests
127 were queued (and serviced) to the device during the reporting
128 interval.
129 r_await
131 The average time in milliseconds that read requests were queued
132 (and serviced) to the device during the reporting interval.
133 w_await
135 The average time in milliseconds that write requests were queued
136 (and serviced) to the device during the reporting interval.
137 %util The percentage of time during the reporting interval that the
139 device was busy processing requests. A value of 100% indicates
140 device saturation.
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143 All are generated on standard error and are intended to be self-
144 explanatory.
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147 Environment variables with the prefix PCP_ are used to parameterize the
148 file and directory names used by PCP. On each installation, the file
149 /etc/pcp.conf contains the local values for these variables. The
150 $PCP_CONF variable may be used to specify an alternative configuration
151 file, as described in pcp.conf(5).
152 For environment variables affecting PCP tools, see pmGetOptions(3).
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156 PCPIntro(1), pcp(1), iostat2pcp(1), pmcd(1), pmchart(1), pmlogger(1),
157 pcp.conf(5) and pcp.env(5).
158Performance Co-Pilot PCP PCP-IOSTAT(1)